1. Field of the Invention
The disclosed concept relates generally to a can bodymaker and, more specifically, to an operating mechanism for a vertically oriented bodymaker.
2. Background Information
Generally, a can, such as but not limited to an aluminum can or steel can, begins as a sheet of metal from which a circular blank is cut. Hereinafter the can will be described as being made from aluminum, but it is understood that the selection of material is not limiting upon the claims. The blank is formed into a “cup.” As used herein, a “cup” includes a bottom and a depending sidewall. Further, while cups and the resulting can bodies may have any cross-sectional shape, the most common cross-sectional shape is generally circular. Accordingly, while it is understood that the cups and the resulting can bodies may have any cross-sectional shape, the following description shall describe the cups, can bodies, punches, etc. as being generally circular.
The cup is fed into a bodymaker including a reciprocating ram and a number of dies. The elongated ram includes a punch at the distal end. A cup is disposed on the punch and passed through the dies which thin and elongate the cup. That is, on each forward stroke of the ram, a cup is initially positioned in front of the ram. The cup is disposed over the forward end of the ram, and more specifically on the punch located at the front end of the ram. The cup is then passed through the dies which further form the cup into a can body. The first die is the redraw die. That is, a cup has a diameter that is greater than the resulting can. A redraw die reshapes the cup so that the cup has a diameter generally the same as the resulting can body. The redraw die does not effectively thin the thickness of the cup sidewall. After passing through the redraw die, the ram moves through a tool pack having a number of ironing dies. As the cup passes through the ironing dies, the cup is elongated and the sidewall is thinned. More specifically, the die pack has multiple, spaced dies, each die having a substantially circular opening. Each die opening is slightly smaller than the next adjacent upstream die.
Thus, when the punch draws the cup through the first die, the redraw die, the aluminum cup is deformed over the substantially cylindrical punch. As the cup moves through the redraw die, the diameter of the cup, i.e., the diameter of the bottom of the cup, is reduced. Because the openings in the subsequent dies in the die pack each have a smaller inner diameter, i.e., a smaller opening, the aluminum cup, and more specifically the sidewall of the cup, is thinned as the ram moves the aluminum through the rest of the die pack. The thinning of the cup also elongates the cup.
Further, the distal end of the punch is concave. At the maximum extension of the ram is a “domer.” The domer has a generally convex dome and a shaped perimeter. As the ram reaches its maximum extension, the bottom of the cup engages the domer. The bottom of the cup is deformed into a dome and the bottom perimeter of the cup is shaped as desired; typically angled inwardly so as to increase the strength of the can body and to allow for the resulting cans to be stacked. After the cup passes through the final ironing die and contacts the domer, it is a can body.
On the return stroke, the can body is removed from the punch. That is, as the ram moves backwardly through the tool pack, the can body contacts a stationary stripper which prevents the can body from being pulled backward into the tool pack and, in effect, removes the can body from the punch. In addition to the stripper, a short blast of air may be introduced through the inside of the punch to aid in can body removal. After the ram moves back to an initial position, a new cup is positioned in front of the ram and the cycle repeats. Following additional finishing operations, e.g., trimming, washing, printing, etc., the can body is sent to a filler which fills the can body with product. A top is then coupled to, and sealed against, the can body, thereby completing the can.
The ram and the die pack are typically oriented generally horizontally. That is, the longitudinal axis of the ram and the axis of the tool pack extends generally horizontally. In this orientation certain components of the bodymaker may be of a relatively simple construction. For example, a cup feeder, i.e., the device that positions cups in the path of ram travel, may rely, in part, on gravity to position a cup on a cup locator for further processing. Throughout this process the cup in the conventional cup feed mechanism is oriented with its axis in a horizontal plane. It is constrained on the sides by guide rails and on both ends by guide plates. When the cup is resting in the cup locator there is an opening present in the open end guide plate to facilitate insertion of the redraw sleeve (a sleeve that clamps the cup against the redraw die and which is hollow to allow the ram to pass therethrough).
Similarly, with a ram traveling in a horizontal direction, the can body take-away device may rely upon gravity to deposit the can bodies on a conveyor. The conveyor consists of a continuously moving chain having a series of rubber “L” shaped attachments. This chain conveyor moves in an upward incline in order to ensure the cans rest in the “L” shaped attachments. The constantly moving conveyor chain is timed such that the fingers of the attachments meet the can at the point it is stripped from the punch and is free to be removed from the bodymaker.
A ram traveling in a horizontal direction, however, has disadvantages. For example, the ram body is a cantilevered body, being coupled at one end to a drive mechanism. In this configuration, the weight of the ram body causes the ram body to droop. This droop may cause a mis-alignment between the ram and the tool pack. This mis-alignment may change over the course of a day, e.g., the ram body may heat up due to use thereby changing the characteristics of the ram which, in turn, change the alignment of the ram. Thus, there is not a simple solution such as repositioning the dies in the tool pack. The ram droop further causes quality problems in the forming of cans by making it difficult to maintain even wall thicknesses. The ram droop also may cause problems when the ram retracts. More specifically, the back side of the punch may contact the ironing dies resulting in abnormal wear to the dies. The ram droop can be mitigated to some degree by making the ram larger in diameter and making the assembly lighter but the tendency to droop will still be evident and using a larger diameter ram would not work when making a small diameter can. Further problems with a conventional bodymaker with the horizontal layout is that it has a relatively large footprint and all bodymakers made to date can only produce one can per cycle per machine. That is, for each revolution of the ram drive mechanism, a single can body is produced. This requires a plant operator to have a large number of machines to meet desired production quotas. Some of these disadvantages may be addressed by utilizing a ram that travels over a generally vertical path.
There is, therefore, a need for a bodymaker wherein the ram does not travel in a direction wherein the ram body may droop. There is a further need for a bodymaker that produces more than one can body per cycle.